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clang-p2996/flang/test/Transforms/stack-arrays.fir
Tom Eccles 7a49d50f22 [flang] support fir.unreachable in stack arrays pass 
Some functions (e.g. the main function) end with a call to the STOP
statement instead of a func.return. This is lowered as a call to the
stop runtime function followed by a fir.unreachable. fir.unreachable is
a terminator and so this can cause functions to have no func.return.

The stack arrays pass looks to see which heap allocations have always
been freed by the time a function returns. Without any returns, the pass
does not detect any freed allocations. This patch changes this behaviour
so that fir.unreachable is checked as well as func.return.

This allows 15 heap allocations for array temporaries in spec2017
exchange2's main function to be moved to the stack.

Differential Revision: https://reviews.llvm.org/D143918
2023-02-14 13:44:59 +00:00

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// RUN: fir-opt --stack-arrays %s | FileCheck %s
// Simplest transformation
func.func @simple() {
%0 = fir.allocmem !fir.array<42xi32>
fir.freemem %0 : !fir.heap<!fir.array<42xi32>>
return
}
// CHECK: func.func @simple() {
// CHECK-NEXT: fir.alloca !fir.array<42xi32>
// CHECK-NEXT: return
// CHECK-NEXT: }
// Check fir.must_be_heap allocations are not moved
func.func @must_be_heap() {
%0 = fir.allocmem !fir.array<42xi32> {fir.must_be_heap = true}
fir.freemem %0 : !fir.heap<!fir.array<42xi32>>
return
}
// CHECK: func.func @must_be_heap() {
// CHECK-NEXT: %[[ALLOC:.*]] = fir.allocmem !fir.array<42xi32> {fir.must_be_heap = true}
// CHECK-NEXT: fir.freemem %[[ALLOC]] : !fir.heap<!fir.array<42xi32>>
// CHECK-NEXT: return
// CHECK-NEXT: }
// Check the data-flow-analysis can detect cases where we aren't sure if memory
// is freed by the end of the function
func.func @dfa1(%arg0: !fir.ref<!fir.logical<4>> {fir.bindc_name = "cond"}) {
%7 = arith.constant 42 : index
%8 = fir.allocmem !fir.array<?xi32>, %7 {uniq_name = "_QFdfa1Earr.alloc"}
%9 = fir.load %arg0 : !fir.ref<!fir.logical<4>>
%10 = fir.convert %9 : (!fir.logical<4>) -> i1
fir.if %10 {
fir.freemem %8 : !fir.heap<!fir.array<?xi32>>
} else {
}
return
}
// CHECK: func.func @dfa1(%arg0: !fir.ref<!fir.logical<4>> {fir.bindc_name = "cond"}) {
// CHECK-NEXT: %[[C42:.*]] = arith.constant 42 : index
// CHECK-NEXT: %[[MEM:.*]] = fir.allocmem !fir.array<?xi32>, %[[C42]] {uniq_name = "_QFdfa1Earr.alloc"}
// CHECK-NEXT: %[[LOGICAL:.*]] = fir.load %arg0 : !fir.ref<!fir.logical<4>>
// CHECK-NEXT: %[[BOOL:.*]] = fir.convert %[[LOGICAL]] : (!fir.logical<4>) -> i1
// CHECK-NEXT: fir.if %[[BOOL]] {
// CHECK-NEXT: fir.freemem %[[MEM]] : !fir.heap<!fir.array<?xi32>>
// CHECK-NEXT: } else {
// CHECK-NEXT: }
// CHECK-NEXT: return
// CHECK-NEXT: }
// Check scf.if (fir.if is not considered a branch operation)
func.func @dfa2(%arg0: i1) {
%a = fir.allocmem !fir.array<1xi8>
scf.if %arg0 {
fir.freemem %a : !fir.heap<!fir.array<1xi8>>
} else {
}
return
}
// CHECK: func.func @dfa2(%arg0: i1) {
// CHECK-NEXT: %[[MEM:.*]] = fir.allocmem !fir.array<1xi8>
// CHECK-NEXT: scf.if %arg0 {
// CHECK-NEXT: fir.freemem %[[MEM]] : !fir.heap<!fir.array<1xi8>>
// CHECK-NEXT: } else {
// CHECK-NEXT: }
// CHECK-NEXT: return
// CHECK-NEXT: }
// check the alloca is placed after all operands become available
func.func @placement1() {
// do some stuff with other ssa values
%1 = arith.constant 1 : index
%2 = arith.constant 2 : index
%3 = arith.addi %1, %2 : index
// operand is now available
%4 = fir.allocmem !fir.array<?xi32>, %3
// ...
fir.freemem %4 : !fir.heap<!fir.array<?xi32>>
return
}
// CHECK: func.func @placement1() {
// CHECK-NEXT: %[[ONE:.*]] = arith.constant 1 : index
// CHECK-NEXT: %[[TWO:.*]] = arith.constant 2 : index
// CHECK-NEXT: %[[ARG:.*]] = arith.addi %[[ONE]], %[[TWO]] : index
// CHECK-NEXT: %[[MEM:.*]] = fir.alloca !fir.array<?xi32>, %[[ARG]]
// CHECK-NEXT: return
// CHECK-NEXT: }
// check that if there are no operands, then the alloca is placed early
func.func @placement2() {
// do some stuff with other ssa values
%1 = arith.constant 1 : index
%2 = arith.constant 2 : index
%3 = arith.addi %1, %2 : index
%4 = fir.allocmem !fir.array<42xi32>
// ...
fir.freemem %4 : !fir.heap<!fir.array<42xi32>>
return
}
// CHECK: func.func @placement2() {
// CHECK-NEXT: %[[MEM:.*]] = fir.alloca !fir.array<42xi32>
// CHECK-NEXT: %[[ONE:.*]] = arith.constant 1 : index
// CHECK-NEXT: %[[TWO:.*]] = arith.constant 2 : index
// CHECK-NEXT: %[[SUM:.*]] = arith.addi %[[ONE]], %[[TWO]] : index
// CHECK-NEXT: return
// CHECK-NEXT: }
// check that stack allocations which must be placed in loops use stacksave
func.func @placement3() {
%c1 = arith.constant 1 : index
%c1_i32 = fir.convert %c1 : (index) -> i32
%c2 = arith.constant 2 : index
%c10 = arith.constant 10 : index
%0:2 = fir.do_loop %arg0 = %c1 to %c10 step %c1 iter_args(%arg1 = %c1_i32) -> (index, i32) {
%3 = arith.addi %c1, %c2 : index
// operand is now available
%4 = fir.allocmem !fir.array<?xi32>, %3
// ...
fir.freemem %4 : !fir.heap<!fir.array<?xi32>>
fir.result %3, %c1_i32 : index, i32
}
return
}
// CHECK: func.func @placement3() {
// CHECK-NEXT: %[[C1:.*]] = arith.constant 1 : index
// CHECK-NEXT: %[[C1_I32:.*]] = fir.convert %[[C1]] : (index) -> i32
// CHECK-NEXT: %[[C2:.*]] = arith.constant 2 : index
// CHECK-NEXT: %[[C10:.*]] = arith.constant 10 : index
// CHECK-NEXT: fir.do_loop
// CHECK-NEXT: %[[SUM:.*]] = arith.addi %[[C1]], %[[C2]] : index
// CHECK-NEXT: %[[SP:.*]] = fir.call @llvm.stacksave() : () -> !fir.ref<i8>
// CHECK-NEXT: %[[MEM:.*]] = fir.alloca !fir.array<?xi32>, %[[SUM]]
// CHECK-NEXT: fir.call @llvm.stackrestore(%[[SP]])
// CHECK-NEXT: fir.result
// CHECK-NEXT: }
// CHECK-NEXT: return
// CHECK-NEXT: }
// check that stack save/restore are used in CFG loops
func.func @placement4(%arg0 : i1) {
%c1 = arith.constant 1 : index
%c1_i32 = fir.convert %c1 : (index) -> i32
%c2 = arith.constant 2 : index
%c10 = arith.constant 10 : index
cf.br ^bb1
^bb1:
%3 = arith.addi %c1, %c2 : index
// operand is now available
%4 = fir.allocmem !fir.array<?xi32>, %3
// ...
fir.freemem %4 : !fir.heap<!fir.array<?xi32>>
cf.cond_br %arg0, ^bb1, ^bb2
^bb2:
return
}
// CHECK: func.func @placement4(%arg0: i1) {
// CHECK-NEXT: %[[C1:.*]] = arith.constant 1 : index
// CHECK-NEXT: %[[C1_I32:.*]] = fir.convert %[[C1]] : (index) -> i32
// CHECK-NEXT: %[[C2:.*]] = arith.constant 2 : index
// CHECK-NEXT: %[[C10:.*]] = arith.constant 10 : index
// CHECK-NEXT: cf.br ^bb1
// CHECK-NEXT: ^bb1:
// CHECK-NEXT: %[[SUM:.*]] = arith.addi %[[C1]], %[[C2]] : index
// CHECK-NEXT: %[[SP:.*]] = fir.call @llvm.stacksave() : () -> !fir.ref<i8>
// CHECK-NEXT: %[[MEM:.*]] = fir.alloca !fir.array<?xi32>, %[[SUM]]
// CHECK-NEXT: fir.call @llvm.stackrestore(%[[SP]]) : (!fir.ref<i8>) -> ()
// CHECK-NEXT: cf.cond_br %arg0, ^bb1, ^bb2
// CHECK-NEXT: ^bb2:
// CHECK-NEXT: return
// CHECK-NEXT: }
// check that stacksave is not used when there is an intervening alloca
func.func @placement5() {
%c1 = arith.constant 1 : index
%c1_i32 = fir.convert %c1 : (index) -> i32
%c2 = arith.constant 2 : index
%c10 = arith.constant 10 : index
%0:2 = fir.do_loop %arg0 = %c1 to %c10 step %c1 iter_args(%arg1 = %c1_i32) -> (index, i32) {
%3 = arith.addi %c1, %c2 : index
// operand is now available
%4 = fir.allocmem !fir.array<?xi32>, %3
%5 = fir.alloca i32
fir.freemem %4 : !fir.heap<!fir.array<?xi32>>
fir.result %3, %c1_i32 : index, i32
}
return
}
// CHECK: func.func @placement5() {
// CHECK-NEXT: %[[C1:.*]] = arith.constant 1 : index
// CHECK-NEXT: %[[C1_I32:.*]] = fir.convert %[[C1]] : (index) -> i32
// CHECK-NEXT: %[[C2:.*]] = arith.constant 2 : index
// CHECK-NEXT: %[[C10:.*]] = arith.constant 10 : index
// CHECK-NEXT: fir.do_loop
// CHECK-NEXT: %[[SUM:.*]] = arith.addi %[[C1]], %[[C2]] : index
// CHECK-NEXT: %[[MEM:.*]] = fir.allocmem !fir.array<?xi32>, %[[SUM]]
// CHECK-NEXT: %[[IDX:.*]] = fir.alloca i32
// CHECK-NEXT: fir.freemem %[[MEM]] : !fir.heap<!fir.array<?xi32>>
// CHECK-NEXT: fir.result
// CHECK-NEXT: }
// CHECK-NEXT: return
// CHECK-NEXT: }
// check that stack save/restore are not used when the memalloc and freemem are
// in different blocks
func.func @placement6(%arg0: i1) {
%c1 = arith.constant 1 : index
%c1_i32 = fir.convert %c1 : (index) -> i32
%c2 = arith.constant 2 : index
%c10 = arith.constant 10 : index
cf.br ^bb1
^bb1:
%3 = arith.addi %c1, %c2 : index
// operand is now available
%4 = fir.allocmem !fir.array<?xi32>, %3
// ...
cf.cond_br %arg0, ^bb2, ^bb3
^bb2:
// ...
fir.freemem %4 : !fir.heap<!fir.array<?xi32>>
cf.br ^bb1
^bb3:
// ...
fir.freemem %4 : !fir.heap<!fir.array<?xi32>>
cf.br ^bb1
}
// CHECK: func.func @placement6(%arg0: i1) {
// CHECK-NEXT: %[[c1:.*]] = arith.constant 1 : index
// CHECK-NEXT: %[[c1_i32:.*]] = fir.convert %[[c1]] : (index) -> i32
// CHECK-NEXT: %[[c2:.*]] = arith.constant 2 : index
// CHECK-NEXT: %[[c10:.*]] = arith.constant 10 : index
// CHECK-NEXT: cf.br ^bb1
// CHECK-NEXT: ^bb1:
// CHECK-NEXT: %[[ADD:.*]] = arith.addi %[[c1]], %[[c2]] : index
// CHECK-NEXT: %[[MEM:.*]] = fir.allocmem !fir.array<?xi32>, %[[ADD]]
// CHECK-NEXT: cf.cond_br %arg0, ^bb2, ^bb3
// CHECK-NEXT: ^bb2:
// CHECK-NEXT: fir.freemem %[[MEM]] : !fir.heap<!fir.array<?xi32>>
// CHECK-NEXT: cf.br ^bb1
// CHECK-NEXT: ^bb3:
// CHECK-NEXT: fir.freemem %[[MEM]] : !fir.heap<!fir.array<?xi32>>
// CHECK-NEXT: cf.br ^bb1
// CHECK-NEXT: }
// Check multiple returns, where the memory is always freed
func.func @returns(%arg0: i1) {
%0 = fir.allocmem !fir.array<42xi32>
cf.cond_br %arg0, ^bb1, ^bb2
^bb1:
fir.freemem %0 : !fir.heap<!fir.array<42xi32>>
return
^bb2:
fir.freemem %0 : !fir.heap<!fir.array<42xi32>>
return
}
// CHECK: func.func @returns(%[[COND:.*]]: i1) {
// CHECK-NEXT: %[[ALLOC:.*]] = fir.alloca !fir.array<42xi32>
// CHECK-NEXT: cf.cond_br %[[COND]], ^bb1, ^bb2
// CHECK-NEXT: ^bb1:
// CHECK-NEXT: return
// CHECK-NEXT: ^bb2:
// CHECK-NEXT: return
// CHECK-NEXT: }
// Check multiple returns, where the memory is not freed on one branch
func.func @returns2(%arg0: i1) {
%0 = fir.allocmem !fir.array<42xi32>
cf.cond_br %arg0, ^bb1, ^bb2
^bb1:
fir.freemem %0 : !fir.heap<!fir.array<42xi32>>
return
^bb2:
return
}
// CHECK: func.func @returns2(%[[COND:.*]]: i1) {
// CHECK-NEXT: %[[ALLOC:.*]] = fir.allocmem !fir.array<42xi32>
// CHECK-NEXT: cf.cond_br %[[COND]], ^bb1, ^bb2
// CHECK-NEXT: ^bb1:
// CHECK-NEXT: fir.freemem %[[ALLOC]] : !fir.heap<!fir.array<42xi32>>
// CHECK-NEXT: return
// CHECK-NEXT: ^bb2:
// CHECK-NEXT: return
// CHECK-NEXT: }
// Check allocations are not moved outside of an omp region
func.func @omp_placement1() {
omp.sections {
omp.section {
%mem = fir.allocmem !fir.array<42xi32>
fir.freemem %mem : !fir.heap<!fir.array<42xi32>>
omp.terminator
}
omp.terminator
}
return
}
// CHECK: func.func @omp_placement1() {
// CHECK-NEXT: omp.sections {
// CHECK-NEXT: omp.section {
// CHECK-NEXT: %[[MEM:.*]] = fir.allocmem !fir.array<42xi32>
// TODO: this allocation should be moved to the stack. Unfortunately, the data
// flow analysis fails to propogate the lattice out of the omp region to the
// return satement.
// CHECK-NEXT: fir.freemem %[[MEM]] : !fir.heap<!fir.array<42xi32>>
// CHECK-NEXT: omp.terminator
// CHECK-NEXT: }
// CHECK-NEXT: omp.terminator
// CHECK-NEXT: }
// CHECK-NEXT: return
// CHECK-NEXT: }
// function terminated by stop statement
func.func @stop_terminator() {
%0 = fir.allocmem !fir.array<42xi32>
fir.freemem %0 : !fir.heap<!fir.array<42xi32>>
%c0_i32 = arith.constant 0 : i32
%false = arith.constant false
%none = fir.call @_FortranAStopStatement(%c0_i32, %false, %false) : (i32, i1, i1) -> none
fir.unreachable
}
// CHECK: func.func @stop_terminator() {
// CHECK-NEXT: fir.alloca !fir.array<42xi32>
// CHECK-NEXT: %[[ZERO:.*]] = arith.constant 0 : i32
// CHECK-NEXT: %[[FALSE:.*]] = arith.constant false
// CHECK-NEXT: %[[NONE:.*]] = fir.call @_FortranAStopStatement(%[[ZERO]], %[[FALSE]], %[[FALSE]]) : (i32, i1, i1) -> none
// CHECK-NEXT: fir.unreachable
// CHECK-NEXT: }
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